*{
    margin: 0;
    padding: 0;
    transition: all 300ms;
    user-select: none;
}
body{
    width: 100vw;
    height: 100vh;
    display: block;
    background-color: #f1f1f1;
}
main{
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    position: absolute;
    display: flex;
    background-color: #f1f1f1;
}
.leftUl{
    margin: 0;
    padding: 0;
    position: relative;
    height: 100vh;
    width: 150px;
    background-color: #333333;
    list-style-type: none;
}
.leftUl li{
    width: 150px;
    padding: 15px 0;
    text-align: center;
    overflow: hidden;
}
.ulTitle{
    margin-bottom: 20px;
    font-size: 20px;
    color: rgb(255, 215, 130);
    font-family: 华文仿宋;
    font-weight: bold;
}
.leftUl li:hover:not(.ulTitle){
    background-color: rgb(92, 92, 92);
}
.leftUl li a{
    padding:10px 40px;
    text-decoration: none;
    color: aliceblue;
}
.leftUl .active{
    background-color: rgb(82, 82, 82);
}
.login,.user,.exit{
    position: absolute;
    bottom: 0;
    width: 150px;
    padding: 15px 0;
    text-align: center;
    overflow: hidden;
    background-color: #333333;
    color: aliceblue;
}
.exit{
    left: -150px;
    background-color: rgb(92, 92, 92);
    color: aliceblue;
    cursor: pointer;
}
.user:hover .exit{
    left: 0;
}

.main {
    position: relative;
    width: calc(100vw - 180px);
    height: calc(100vh - 30px);
    left: 15px;
    top: 15px;
    animation: slideIn 0.5s ease-in-out;
}

@keyframes slideIn {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}
@keyframes tipsIn {
    0% {
        opacity: 0;
        top: 20px;
    }
    10%{
        opacity: 1;
    }
    70% {
        opacity: 1;
        top: 20px;
    }
    100% {
        opacity: 0;
        top: -100px;
    }
}
.alert{
    position: absolute;
    top: -100px;
    left: 50vw;
    padding: 10px 50px;
    width: fit-content;
    height: 55px;
    background-color: rgba(255, 255, 255, 0.5);
    z-index: 999;
    animation:  tipsIn 2.5s ease-in-out;
    opacity: 1;
}